The present invention relates to a method of carrying a radioactivated large-sized apparatus out of a reactor building of a nuclear power plant and, more particularly, to a method suitable for carrying out a reactor pressure vessel.
A first prior art relating to carrying out a reactor pressure vessel is disclosed in JP A 6-230188 which discloses a method in which a reactor pressure vessel is hung up inside an air lock provided on a roof of a reactor building and fixed to the air lock by a fixing tool, and the air lock and the reactor pressure vessel integrated therewith are moved under the condition that the inside of the air lock is kept at vacuum.
A second prior art relating to carrying out a reactor pressure vessel is disclosed in JP A 8-62368 which discloses a method in which a clean room adjacent to a reactor building and covering an opening portion of its roof is provided, and in-reactor structures, a control rod driving mechanism housing and a reactor pressure vessel are integrated and moved inside the clean room to be carried out. JP A 8-62368 also discloses a method in which the in-reactor structures, the control rod drive housing, a reactor pressure vessel and a xcex3 shield are integrated and moved inside the clean room and carried out.
A third prior art relating to carrying out of a reactor pressure vessel is disclosed in JP A 9-145882 which discloses a method in which while hanging up a large-sized block in which in-reactor structures and a control rod drive housing are integrated, a cylindrical shield is mounted on its outer surface, and the large-sized block is sealed with this shield and carried out of a reactor building.
The reactor pressure vessels to which the above-mentioned prior art are applied are large-sized apparatus each reaching a height of about 25 m, diameter of about 6 m and weight of about 1,000 tons, for example. Further, the xcex3 shield, that is, a reactor shield wall, which is a radiation shield for a reactor pressure vessel, is a large-sized apparatus reaching a weight of about 400 tons.
In the first prior art, the air lock is large-sized equipment and it is necessary to keep a vacuum inside the large-sized air lock. Therefore, works for carrying out the reactor pressure vessel, including the equipment of air lock and management of vacuum, are complicated and need a long time.
In the second prior art, it is necessary to provide a clean room which is larger in scale than the air lock of the first prior art. Therefore, works for carrying out the reactor pressure vessel including the clean room are complicated and need a longer time.
As for the third prior art, a concrete shield mounting method is not disclosed. Further, there is the possibility that a dose of radiation exposed to a worker when the shield is mounted on the reactor pressure vessel increases.
An object of the present invention is to provide a method of carrying out a large-sized apparatus, in which when a radioactivated large-sized apparatus is carried out of a reactor building, a shield can be easily mounted on the large-sized apparatus in a short time and an exposure dose to a worker or operator when the shield is mounted can be reduced.
A first embodiment resides in a large-sized apparatus carrying out method of carrying out a radioactivated large-sized apparatus from a reactor building of a nuclear power plant, which method comprises: providing a first opening portion for carrying out the large-sized apparatus in a region, positioned at an upper portion of the large-sized apparatus, of a roof of the reactor building; carrying a radiation shield for covering the large-sized apparatus and shielding radiation into the reactor building through the first opening portion, and installing the radiation shield on an upper side of the large-sized apparatus; lowering a hanger for hanging up the large-sized apparatus through the first opening portion and a second opening portion provided on an upper end portion of the radiation shield; abutting a part of the upper end portion of the large-sized apparatus and a part of the upper portion of the radiation shield by raising the large-sized apparatus by the hanger; and hanging up and carrying the large-sized apparatus and the radiation shield integrated therewith out of the reactor building.
A second embodiment resides in a large-sized apparatus carrying out method of carrying out radioactivated reactor pressure vessel from a reactor building of a nuclear power plant, which method comprises: providing a first opening portion for carrying out the reactor pressure vessel in a region, positioned at an upper portion of the reactor pressure vessel, of a roof of the reactor building; carrying a radiation shield for covering the reactor pressure vessel and shielding radiations into the reactor building through the first opening portion, and installing the radiation shield on an upper side of the reactor pressure vessel; lowering a hanger for hanging up the reactor pressure vessel through the first opening portion and a second opening portion provided on an upper end portion of the radiation shield; abutting a part of the upper end portion of the reactor pressure vessel and a part of the upper portion of the radiation shield by raising the reactor pressure vessel by the hanger; and hanging up and carrying the reactor pressure vessel and the radiation shield integrated therewith out of the reactor building.
A third embodiment resides in a large-sized apparatus carrying out method as set forth in the second embodiment, wherein the reactor pressure vessel and the radiation shield are integrated and carried out of the reactor building under the condition that incidental apparatus are mounted on the reactor pressure vessel.
A fourth embodiment resides in a large-sized apparatus carrying out method as set forth in the second embodiment, wherein the reactor pressure vessel and the radiation shield are integrated and carried out of the reactor building under the condition that the reactor pressure vessel is covered with the radiation shield as far as the vicinity of an upper end portion of a skirt of the reactor pressure vessel.
A fifth embodiment resides in a large-sized apparatus carrying out method as set forth in the second embodiment, wherein the reactor pressure vessel and the radiation shield are integrated and carried out of the reactor building under the condition that reactor water is contained in the reactor pressure vessel.
A sixth embodiment resides in a large-sized apparatus carrying out method as set forth in the second embodiment, wherein the radiation shield is provided with a stopper at the upper end portion thereof, a part of a lid of the reactor pressure vessel and the stopper are abutted, and the reactor pressure vessel and the radiation shield are integrated and hung up.
A seventh embodiment resides in a large-sized apparatus carrying out method as set forth in the second embodiment, wherein the radiation shield is constructed so that a plurality of cylindrical shields covering the reactor pressure vessel are made in multi-layers.
An eighth embodiment resides in a large-sized apparatus carrying out method of carrying out of a radioactivated cylindrical reactor pressure vessel from a reactor building of a nuclear power plant, which method comprises: providing a first opening portion for carrying out the reactor pressure vessel in a region, positioned over the reactor pressure vessel, of a roof of the reactor building; carrying a cylindrical radiation shield for covering the reactor pressure vessel and shielding radiations into the reactor building through the first opening portion, and installing the cylindrical radiation shield on a reactor shield wall; lowering a hanger for hanging up the reactor pressure vessel through the first opening portion and a second opening portion provided on an upper lid of the radiation shield; abutting a part of a lid of the reactor pressure vessel and a part of the upper lid of the radiation shield by raising the reactor pressure vessel by the hanger; and hanging up and carrying the reactor pressure vessel and the radiation shield integrated therewith out of the reactor building.